WSJT-X/getsnr.f

      subroutine getsnr(x,nz,snr)

      real x(nz)

      smax=-1.e30
      do i=1,nz
         if(x(i).gt.smax) then
            ipk=i
            smax=x(i)
         endif
         s=s+x(i)
      enddo

      s=0.
      ns=0
      do i=1,nz
         if(abs(i-ipk).ge.3) then
            s=s+x(i)
            ns=ns+1
         endif
      enddo
      ave=s/ns

      sq=0.
      do i=1,nz
         if(abs(i-ipk).ge.3) then
            sq=sq+(x(i)-ave)**2
            ns=ns+1
         endif
      enddo
      rms=sqrt(sq/(nz-2))
      snr=(smax-ave)/rms

      return
      end